About the Project

The Stratford 115kV Railroad Transmission Line Upgrade Project rebuilds UI’s transmission lines along the Metro North Railroad(MNR) corridor between Baird Substation, Barnum Substation and the Devon Tie Switching Yard, for a total distance of approximately 2.4 miles. This includes installation of 63 new foundation supported galvanized transmission poles, upgrading of conductor size and installing two sectionalizing switches at Barnum Substation. This project will enhance the structural integrity and reliability of the high voltage transmission lines along the MNR corridor allowing UI to continue to provide safe, reliable electric service to our customers for years to come.

Project Purpose and Need

The ISO New England* Southwest Connecticut Transmission Planning study identified that under certain conditions, the reliability of the area transmission system may be at risk. The 115kV transmission lines between Devon Tie and Baird Substation may be subject to damaging overloading conditions which will impact the system reliability exposing the electric system and our customers to unacceptable reliability risks. Due to the physical limitations of the existing MNR structural support system which was originally installed in the early 1900’s, coupled with the reliability risks, it was recommended that new transmission lines be installed on new galvanized steel monopoles, along this 2.4-mile transmission corridor.

*ISO(Independent System Operator) New England is an independent, non-profit Regional Transmission Organization created to assure the region has reliable, competitively priced wholesale electricity across the six New England States.

Project Map

Project Scope

  • Staking, vegetation clearing, installation and removal of access roads and work pads 
  • Installation of drilled foundations supporting monopoles and conductor
  • Installation of 2 sectionalizing switches at the Barnum Substation to increase reliability and operational flexibility
  • Removal of bonnet structures (top of poles which hold the power lines) on MNR Catenaries (cables which hold the lines)
  • Site Restoration

Benefits to region and our customers

The upgrades will improve the reliability and resiliency of the transmission system, ensuring that the safe and reliable transmission of power is maintained throughout Fairfield and New Haven County in accordance with Federal reliability standards.


Construction start: Dec. 2019
Estimated in-service date: 2021 Q3

Construction Process

UI is committed to working cooperatively with our customers, neighbors, community leaders and regulators as we improve reliability while minimizing disruption to the environment and community. We have a dedicated team of public outreach liaisons who will be involved throughout the duration of the project to answer any questions you may have.

Below are the stages of the project construction process that you may see in your community.


1) Laying matting and building access roads for construction vehicles while protecting the area

2) Tree clearing – trimming "danger trees" that may cause service interruption

3) Drilling foundations which will support the new galvanized steel poles

4) Setting the bolt cage for the foundation structure

5) Pouring concrete for the foundations

6) Final concrete cap for the H-frame foundations

7) Setting the poles into the foundation

8) Stringing the wire (conductor) onto the poles

9) Restoration - grading, seeding & mulch. Access roads removed.

Updated May 2020

Railroad Transmission Line Upgrade Video


UI is designing the Project to avoid and minimize negative impacts to the community and the environment. Early Project planning efforts included the completion of a set of resource assessments to clarify important planning considerations such as water resources; soil characteristics; cultural resources; and sensitive plant and animal species. Active regulatory coordination and reviews preceded numerous permitting efforts and are ongoing through the construction phase of the Project. UI has secured the necessary authorizations reviews and permits from agencies across federal, state and local administration agencies. Consultations and permits have been pursued from the following agencies for the Project:


  1. U.S. Army Corps of Engineers (USACE)
  2. U.S. Fish and Wildlife Service (USFWS)
  3. U.S. Environmental Protection Agency (EPA)
  4. Federal Aviation Administration (FAA)

State of Connecticut

  1. Connecticut Siting Council (CSC)
  2. Connecticut Department of Energy & Environmental Protection (CTDEEP)
  3. Connecticut State Historic Preservation Office (SHPO)

Local and Regional

  1. Town of Stratford

Document Library

Title Date
Outreach Log 05/20/2020
Fact Sheet 05/01/2020
Raymark/Contract Plating Info sheet 05/01/2020

How the Electric Delivery System Works

The electric grid consists of high-voltage transmission lines and low-voltage distribution lines that transport electricity from power generation plants to community areas that need electricity.

United Illuminating (UI)

United Illuminating (UI) is a subsidiary of AVANGRID. Established in 1899, UI is engaged in the purchase, transmission, distribution and sale of electricity and related services to approximately 335,000 residential, commercial and industrial customers in the greater New Haven and Bridgeport areas of Connecticut. UI's service territory includes 17 Connecticut towns and cities in an area totaling 335 square miles along or near the shoreline of Long Island Sound.

For more information, visit uinet.com and avangrid.com

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